Composite metal structural components



of fine wires or filaments of higher United States Patent 3,314,825COMPOSITE METAL STRUCTURAL COMPONENTS Peter Joseph Forsyth, Farnham,Surrey, and Ronald Walter George, Dennis Arthur Ryder, and Robin EdwinVian, Farnborough, England, assignors to National Research DevelopmentCorporation, London, England, a British corporation No Drawing. FiledMay 20, 1963, Ser. No. 281,755 Claims priority, application GreatBritain, May 24, 1962, 19,984/ 62 16 Claims. (Cl. 14812.7)

This invention relates to composite manufactured metallic structuralmaterials. It is particularly but not exclusively applicable to sheetmaterial.

It is commonly it not usually the case that such structural material isdesigned and made with special regard to the loads which it will have tobear in use. However, with conventional homogeneous materials, thevarious inter-related factors affecting the desired performance of thematerial cannot all be taken simultaneously fully into account becauseof the physical problems which would arise. As a simple example,dimensional and weight requirements will necessarily limit otherproperties of a given component made of a given material. Thedeficiencies of homogeneous materials are particularly apparent whenconsidering the fatigue resistance properties of metallic sheetmaterials.

In order to try and overcome these deficiencies composite metallicmaterials having special properties have previously been proposed. Thus,for example the use of sandwich sheet materials in which the centrelayer has the greatest ductility has been described in the provisionalspecification of copending patent application No. 44,226/60, now U.S.Patent No. 996,387, as a means of improving the fatigue resistance ofsheet material.

According to the present invention a composite metallic structuralmaterial comprises a metallic matrix and a relatively higher strengthreinforcing component unalloyed with but embedded in the matrix and inthe form tensile strength than the matrix.

The matrix may be a sheet and the reinforcing wires are preferablygenerally in the plane of the sheet and preferably have a specificpredetermined orientation.

The wires or filaments of the reinforcing component may be made up as awoven or knitted mesh.

The wires of the reinforcing component are preferably as thin aspossible and their proportion of and arrangement in the compositematerial is initially calculated in accordance with the desired strengthand weight properties of the material.

Advantageously the woven type reinforcing component is made with higherstrength wires arranged in preferred predetermined positions ordirections. Thus, for example, the warp or weft threads, or some only ofthe warp or weft threads, or some of both warp and weft threads, may beof higher strength wire and the re mainder of lower strength wire. Inone such arrangement which has given good results, the whole of the Warpthreads were of higher strength wire and the whole of the weft threadswere of a lower strength soft metal wire capable of alloying with themetal of the sheet component under hot manufacturing or heat treatmentconditions. In a particular example the weft threads were of softaluminium and the sheet component was an aluminium alloy, the aluminiumwires becoming alloyed with the alloy sheet component during a solutionheat treatment process.

For some composite materials it may be essential to increase theproportion or density of distribution of the higher strength wires. Thismay be achieved by interposing two or more contiguous layersof'the wireremforcing component between any two of the sheet components.

In the case of aluminium alloy sheet materials, a percentage ofstainless steel wires as low as 1% by volume of about 0.015 in. diameterhas resulted in a very great improvement of fatigue properties.

described.

In general, the methods of manufacture involve the cleansing of thecomponents by suitable pickling or other chemical methods, stacking thesheet and wire comsheet matrix component Regarding hot rolling, thestack may be passed through the rolls in any direction in relation tothe orientation of the individual wires of the reinforcing component butif,

r for example, heavy reductions of thickness during rolling are to bemade it is preferred that rolling should take place with the highstrength wires parallel with the axis of the rolls so that longitudinalbreakage of these wires by excessive extension during rolling isobviated In one method of manufacturing thecomposite sheets of theinvention a sheet component is wrapped in the Wire reinforcingcomponent, the latter being in mesh form if desired, and the assembly issandwiched between two further sheets of the lower strength metal sheetand the whole hot rolled to give a single composite sheet.

In another method a woven mesh of wire is sandwiched between two sheetsof the lower strength metal sheet and the assembly hot rolled as beforeto give a single composite sheet.

In yet another method a wire mesh of metal is used as a core or matrixon which lower strength metal is deposited, the composite sheetthereafter being cold or hot rolled to final form. The depositionprocess may be a hot spraying or electro-chemical process.

In the case of aluminium or aluminium alloy sheet ma terials, a typicalhot rolling temperature range is 400-to 450 C. Where such alloys arereinforced with a wire mesh component including high strength wires andsoft aluminium wires, a subsequent solution heat treatmeritat 500 C.followed by quenching may be employed, in which step the aluminium wireslose their separate identity becoming alloyed with the sheet matrixmaterial. After rolling, the composite sheets may be stretchedstraightened in the usual way and age hardened at about C., or a similartemperature as is appropriate to'the nature of the material of the sheetmatrix component.

The above mentioned methods all permit the construction of a compositesheet in which the elements of the reinforcing wire component arestrategically arranged with respect to the expected nature anddirections of application of working loads.

Several examples of the invention will now be described. The examplesrelate to the three methods of construction briefly described above andinclude experimental results of were put. The tests results will beshown in tabular form.

The materials employed were high strength aluminium alloy sheet materialto specifications a, D.T.D. 687; nominal composition Cu 0.4, Mn 0.5, Mg2.7, Zn 5.3, A1 balance, b, L. 73 nominal composition Cu 4.4, Mn 0.6, Mg0.6, Si 0.7, Al balance of thickness in the range 0.012

physical tests to which the products to 0.030 inch and stainlessdiameter in the range 0.002 to The methods employed were: (a) Wrappingan aluminium with wire then placing sheets and hot rolling the asse therange 400 to 450 (b) Hot rolling a high strength wires,

wires and soft aluminium wires (d) Filling the interstices sheet matrixmaterial.

each batch of the usual manner. carried out on 10" ating tension at astress steel and tungsten wire of 0.015 inch.

of the sheet.

The crack length and the number of stress cycles applied were recordedon the same frame of a cine film at suitable intervals throughout thetest.

or aluminium alloy sheet TABLE I The test results on specimens of thematerials it between two additional alloy 5 were as follows:

produced Fatigue lite 0.1% proof U.T.S., tons/ Elongation, (cycles toMaterial stress, tons/ sq. in. percent failure at sq. in. 18,000+2,000

p.s.i.)

(9) D'ID 687A (Clad) 20.2 33. 7 12. 5 120,000 (10) Wire wound purealuminium sheet rolled between two DTD 687A sheets 30. 4 36. 8 12. 0287, 000 (11) DT'D 687A three-ply material with wire wrapped centralsheet 28. 4 33. 6 13. 0 196,000 (12) Two D'ID 687A sheets with wire meshcentre 30. 3 33.1 1. 5 312,000 (13) DTD 687A with alumin iurn sprayedmesh at centre. 25. 6 30.1 2.0 289,000 (14) As 13 but mesh laid in at tosheet axis 32. 2 36. 5 8. 0 544, 000 (15) 3 ply to L73 specification.25.9 30. 2 12.0 1,188,940 (16) Two L73 sheets with wire mesh at centrelaid in at 4 to sheet axis TABLE II 0.1% proof Modulus of Materialstress, tons] U .T .S Elongation, Elasticity,

sq. in. tons/sq. in. percent Ex. 10

lb./sq. in. Room temperature:

Control specimen, sheet L73 10.0 10.3 (i) L73 sheet combined as in (0)above with 6% by volume of stainless steel wires of diameter 0.007 in.cross rolled but tested longitudinally of the wires 6. 5 11.9 At 200 C.:

(ii) Control specimen, sheet L73 8. 4 (iii) Asi 22.0 8 11.2 At 250 C.:

(iv) Control specimen, sheet L73 6. 0 (v) Asl 14.0 5.0 11.0 At 300 C.:

(vi) Control specimen, sheet L73 5. 5 5. 0 (vii) Asi u 4.5 8.0

Room temperature:

(viii) As i but with 12% by volume of stainless steel wires mbly at atemperature in The improvement in the prope rties of the composite C. togive a single composite sheet, sheet materials compared with the sheetmatrix materials sheet of wire mesh between two may also be expressed interms of specific strength and sheets of aluminium alloy the rollingbeing performed in specific modulus of elasticity which take intoaccount the some cases along and some cases across the length of thespecific gravity of the composite material. The following dataillustrate this feature of the composite materials.

(0) Hot rolling a composite stack including outer sheet TABLE III matrixlayers of thickness 0.030 inch and several interleaved alternate innerlayers of sheet matrix material of Materi 1 T t thickness 0.012 inch andmeshes of woven stainless steel a empem me 553%. 523311 of diameter0.007 inch, of a piece of wire mesh by L73 (control specimen) Roomtemp..- 10.75 as aluminium spraying before rolling it between alloysheets. gg: g 5 In general the hot rolling was continued to reduce theAs ix T 10:; 31% thickness of the composite material to 0.063 inch. Thecomposite wire reinforced sheets of (a), (b), (0) A81 ii? 23 and (d)were solution heat treated, stretched and aged 3% in accordance with theappropriate specifications of the Microsections from each sheet werealso examined and wire reinforced sheets were 211- It will be seen thatthere is a marked improvement in ways radiographed. Tensile test pieceswere taken from the fatigue life of the specimens with but slight yettoleramaterial produced and these were tested in ble decreases inisolated instances of some of the other Fatigue crack propagation testswere properties. x 6 /2 x 0.064" panels tested in fluotu- We claim:

of 18,000i2000 si. Each speci 1. A method of producing a compositemetallic matemen had a central slot normal to the axis of tension sorial comprising assembling in a stack at least two matrix that a crackgrew from each of its ends towards the edges layers of relatively lowstrength metal and at least one intervening reinforcing layer of finewires, which layer includes at least a proportion of relatively highstrength fine sheet form, the

geneous composite material including the embedded high strength wires.

2. A method of producing a composite metallic material comprisingassembling in a stack at least two matrix high strength 3. A method ofprod high strength wires.

4. A method as claimed in claim 1 in which compacting is done by hotrolling.

5. A method as claimed in claim 2 in which compacting is done by hotrolling.

6. A method as claimed in claim 3 in which the woven mesh includes warpthreads of relatively high strength and weft threads of relatively lowstrength.

7. A method threads are assembly of the stack.

8. A method as claimed in claim 7 in which compacting is done by hotrolling the stack.

9. A method as claimed in claim 8 in which the hot rolling is done sothat p and then collectively stacked between the external matrix layers.

11. A method as claimed in claim 10 in which compacting is done by hotrolling the stack.

12. A method as claimed in claim 11 in which the direction in which thestack passed though the rolls is such as to maintain the high strengthWires substantially parallel with the axes of the rolls.

13. A method of high stren matrix sheet material.

16. A method as claimed in claim 15 in which the reinforcing wire layeris of woven construction including H. F. SAITO, Assistant Examiner

13. A METHOD OF PRODUCING A COMPOSITE MATERIAL OF A HIGH STRENGTHALUMINIUM ALLOY AND A REINFORCEMENT OF ANOTHER METAL COMPRISINGASSEMBLING IN A STACK EXTERNAL RELATIVELY THICKER SHEET MATRIX LAYERS OFALUMINIUM ALLOY AND SANDWICHED BETWEEN THE EXTERNAL LAYERS AT LEAST ONEREINFORCING LAYER INCLUDING AT LEAST A PROPORTION OF RELATIVELY HIGHERSTRENGTH SUBSTANTIALLY PARALLEL FINE WIRES SELECTED FROM THE GROUPCONSISTING OF STAINLESS STEEL, TUNGSTEN AND COBALT ALLOY WIRES, WHICHPROPORTION CONSTITUTES FROM 1 TO 20% BY VOLUME OF THE COMPOSITEMATERIAL, HOT ROLLING THE ASSEMBLED STACK AT A TEMPERATURE IN THE RANGE400 TO 450*C. WITH THE HIGHER STRENGTH WIRES PARALLEL WITH THE ROLL AXESTO CONVERT THE STACK INOT COMPOSITE SUBSTANTIALLY HOMOGENEOUS SHEETMATERIAL CONTAINING THE EMBEDDED HIGH STRENGTH WIRES AND SOLUTION HEATTREATING AND AGE HARDENING THE COMPOSITE SHEET AT TEMPERATURESAPPROPRIATE TO THE TREATMENT OF THE MATRIX MATERIAL.